Fixing and buying guide

What this product is and who needs it

Twin and combination flashings are metal flashings used to seal gaps and joints where roof penetrations or changes in roof plane occur. They are essential components in pitched roof construction, preventing water penetration at vulnerable points. These flashings are for builders, roofers, and serious DIY customers installing or maintaining pitched roofs with complex angles and curves. They work alongside other VELUX products as part of a complete roof system.

Compatibility and sizing

This flashing is sized at 55 x 118cm (21.6 x 46.1 inches) and is designed for use with timber roof structures of grade F16 or higher. The product is also compatible with metal roofing systems. Before purchase, confirm your roof timber grade and measure the area requiring flashing to ensure this size suits your installation. Check that your roof structure can accommodate the flashing dimensions and that it aligns with other VELUX components in your system.

• Size: 55 x 118cm
• Suitable for timber grade F16 or higher
• Compatible with metal roofing systems
• Designed for pitched roofs with complex angles and curves

Material and durability

The flashing is constructed from galvanized steel with a PVC coating and powder-coated finish. This combination provides robust protection against corrosion and weather exposure. The galvanized steel base offers structural strength whilst the PVC coating and powder coat finish deliver additional weather resistance and durability on exposed roof surfaces.

• Galvanized steel construction with PVC coating
• Powder-coated finish for enhanced protection
• Designed to resist wind-driven rain and snow

Pre-installation checks and preparation

Before fixing, inspect your roof structure to confirm timber grade F16 or higher is present. Ensure the roof area is clean and dry, and that the flashing dimensions align with your roof penetration or joint. Check that all other VELUX components in your system are compatible with this flashing size. Have appropriate fixings and sealants ready, and ensure you have safe access and working platforms in place before beginning installation on a pitched roof.

• Verify roof timber grade meets F16 minimum requirement
• Clean and dry the installation area thoroughly
• Confirm flashing dimensions suit your roof penetration or joint
• Check compatibility with other VELUX roof products